Asphalt cement is an important large volume commodity which is generally derived from petroleum refinery streams such as vacuum residua.
Air-blownig is normally required to increase the viscosity and lower the penetration number of the asphaltic material. During the air-blowing process, thermal and oxidative polymerization is effected, and the lower molecular weight resins are converted to asphaltenes.
Recent international economic developments have signaled the inevitable decline of petroleum as the world's supreme industrial commodity. The price of raw petroleum has increased several fold. Also, the consumption of petroleum has been increasing exponentially, and concomitantly the world petroleum supply has diminished to less than several decades of proven reserves.
The economics of upgrading petroleum refining residua into asphalt cement and other high value products is of increasing concern. Attention is being directed to coal-derived liquids as a potential abundant source of asphaltenes.
It was recognized by early workers that coal can be liquified by controlled heating in the substantial absence of oxygen. The conversion products are a liquid and a char. Because of the new compelling economic factors, the technology of coal liquefaction and gasification has been expanding at an accelerated pace. Pioneer developments in the field are represented by Lurgi and Fischer-Tropsch technology. More recent advances in coal liquefaction are described in United States Patents Nos. 1,904,586; 1,955,041; 1,996,009; 2,091,354; 2,174,184; 2,714,086; 3,375,188; 3,379,638; 3,607,718; 3,640,816; 3,642,608; 3,705,092; 3,849,287; 3,870,621; inter alia.
It is one view that liquefaction of coal proceeds via an asphaltene complex intermediate: EQU coal .revreaction. asphaltene .revreaction. oil
The prospective advantages of combining coal-derived materials with petroleum-derived materials have not been realized because of the general incompatibility of the two different categories of carbonaceous minerals.
Hence, there remains a pressing need for new technology to alleviate the dependence of industrial nations on petrioleum as a critical raw material in energy and chemical applications, and a need for new technology to enhance the efficient conversion of petroleum refinery residua into valuable industrial products.
Accordingly, it is an object of the present invention to improve the economics of upgrading low value refractory petroleum residua into important industrial commodities.
It is another object of the present invention to provide a method for producing homogeneous blends of coal-derived and petroleum-derived materials.
It is a further object of the present invention to provide a novel asphalt cement produced from coal-derived carbonaceous material.
Other objects and advantages of the present invention shall become apparent from the accompanying description and examples.